NISKAYUNA — A discovery last year of a thumb drive hidden in a book at the Niskayuna High School library led to accusations of at least one male student secretly filming female students, according to paperwork filed in court.

An investigation led to the arrest two students over the past year, Christopher Khan and Angelo A. Cavallaro.

Cavallaro, 18, is facing charges related to images of alleged child pornography discovered during the investigation, images believed to have been downloaded from the internet, prosecutor John Carson said.

Cavallaro, charged in January, faces three felony counts of possession of a sexual performance by a child. His case remains pending in Schenectady County Court. James Knox, Cavallaro’s listed attorney, could not be reached for comment.

Charges against Khan are contained in paperwork filed in Cavallaro’s case. Officials said Friday that Khan faces one count each of attempted unlawful surveillance and endangering the welfare of a child, both misdemeanors. The status of his case could not be determined Friday. Paperwork indicates police charged Khan in June 2015.

Kathryn Conklin, the attorney for Khan, said she could not comment on the case.

According to paperwork filed in Cavallaro’s felony case, Khan allegedly admitted to police that he took pictures and videos of Niskayuna High School students without their knowledge or consent. He also allegedly admitted to owning the thumb drive and to selling the pictures to Cavallaro.

Angelo A. Cavallaro

Police later questioned Cavallaro and he allegedly admitted to paying Khan for a picture or video, but said he did it once, not multiple times.

Carson on Friday said that any images related directly to students continue to be investigated.

Police officials could not be reached for comment Friday.

The Niskayuna Central School District issued the following statement:

“There is nothing we take more seriously than the well-being of our students and maintaining a safe environment for them. As soon as we became aware of potential criminal activity we notified law enforcement, which handled the investigation from there. We will continue to cooperate with law enforcement whenever necessary on behalf of the well-being of our students and school community.”

Cavallaro is currently listed as a freshman member of the SUNY Oneonta track team on that school’s website.

According to a Niskayuna police investigation narrative, the following took place:

The investigation began on April 15, 2015, when a parent volunteer putting books away in the school’s library spotted a book on a shelf without a barcode. The volunteer inspected the book further and found a cutout inside that contained a thumb drive.

In an attempt to find the thumb drive’s owner, staff opened the drive and “observed folders that contained images and videos of students along with names.”

Further inspection found folders containing images and videos, as well as “a list of female student names.”

Town police contacted state police for help in analyzing the drive. The drive showed “images of possibly a 10-year-old female … along with many other females believed to be under the age of 16 years old”

Police also found a male with prom pictures and “pictures/video of him masturbating on an airplane.” The drive also contained screen shots of text messages referring to Khan.

Town police then called in Homeland Security Investigations for assistance.

Police received a search warrant for Khan’s family residence on Sandra Lane and interviewed him June 3, 2015, court filings said.

In addition to allegedly admitting to owning the thumb drive, he told police that Cavallaro had “contacted him several times to take voyeurism, candid and up-skirt photos and videos of females.”

Most recently, he told police he had tried that at Niska Day, May 16, 2015, with a female who confronted him about it.

Police then obtained a search warrant for Cavallaro’s Balltown Road residence and a secondary residence on Van Vranken Avenue in Schenectady.

Cavallaro allegedly told police that he had seen child pornography on the internet, but didn’t believe he had any on his computer. Charges filed allege he possessed child pornography images on his laptop recovered from his Van Vranken Avenue address.

Cavallaro also allegedly told police he was “aware of Dropbox accounts with nude images of NHS females but they did not belong to him.” He denied knowledge of the thumb drive.

Police subpoenaed Dropbox for the accounts. Results of that were not included in court paperwork.

After Khan was arrested he was ordered to stay away from all school district grounds.